ORIGINAL ABSTRACT

Rapid, sensitive and selective method was studied for the determination of glyphosate in rice and wheat flour using a Raptor Polar column. Samples were extracted with acidified methanol solution. Isotope labeled internal standard was added with the extraction solvent to ensure accurate tracking and quantitation. The glyphosate was analyzed by liquid chromatography tandem mass spectrometry using a Raptor Polar column. Method performance was evaluated through a series of parameters that include accuracy, precision, linearity, limit of detection (LOD), limit of quantitation (LOQ) and matrix effect. Mean recoveries for all matrices were within 96-116% at three fortification levels. Precision for replicates was ≤19% relative standard deviation (RSD%) for wheat and ≤9% RSD% for rice across all fortification levels. Linearity was good for both matrices with a correlation coefficient >0.999 and residual <20% in the concentration range 0.025-1 mg kg-1. LOD was 0.005 mg kg-1for both rice and wheat flour and the LOQ was 0.05 mg kg-1for both matrices. The matrix effect was also studied. A successful method for the analysis of glyphosate in wheat and rice flour assure that the criteria of acceptability of the maximum residue levels (MRLs) are insured.